Operational devices for longitudinally adjustable gas springs are used in office chairs, especially to facilitate in a release position the relative motion of two chair parts to one another, corresponding to the body movements of the user, and secondly to be able to adjust optionally in a locking position a steady positioning of the two chair parts relative to one another.
ln addition, the release tappet of the gas spring, which is placed in this longitudinally shiftable spring, can be secured in two different positions. In order to effect this, it is conventional to employ a control lever that acts on a release tappet and is adjustable in two different end positions by means of a crank guide.